# What is Sudoku: Definition and 26 Discussions

Sudoku (数独, sūdoku, digit-single) (, , , originally called Number Place) is a logic-based, combinatorial number-placement puzzle. In classic sudoku, the objective is to fill a 9×9 grid with digits so that each column, each row, and each of the nine 3×3 subgrids that compose the grid (also called "boxes", "blocks", or "regions") contains all of the digits from 1 to 9. The puzzle setter provides a partially completed grid, which for a well-posed puzzle has a single solution.
French newspapers featured variations of the Sudoku puzzles in the 19th century, and the puzzle has appeared since 1979 in puzzle books under the name Number Place. However, the modern Sudoku only began to gain widespread popularity in 1986 when it was published by the Japanese puzzle company Nikoli under the name Sudoku, meaning "single number". It first appeared in a U.S. newspaper, and then The Times (London), in 2004, thanks to the efforts of Wayne Gould, who devised a computer program to rapidly produce unique puzzles.

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1. ### Sudoku solver by graph coloring theory

Hello everybody! I have to implement a sudoku solver in C ++ taking advantage by graph coloring theory, where each number to insert is a color of the associated graph node. In particular I would like to use the Welsh-Powell algorithm. I find myself in trouble starting with this project and I...
2. ### I Interesting Article Ref: Sudoku and Linear Algebraic aspects

Hi, This looked interesting. Determinant and Linear-Algebraic aspects of Sudoku puzzles: http://www.student.montefiore.ulg.ac.be/~merciadri/docs/papers/sudoku.pdf
3. ### A P vs NP Guessing and process of elimination

If we suppose there is an algorithm for P vs NP, would it have to be able to find solutions where we now use trial and error? In harder Sudokus, for example, there are times when you have two or more possible numbers and need to guess whereafter you work the rest of the numbers through to see if...
4. ### A Identifying Features in Trouble Sudoku Puzzles: Techniques for Classification

Hi All, I am trying to identify features in Sudoku puzzles that separate the "trouble" ones that are hard for me from the ones that are not. But I am having trouble finding techniques to do this. I have been a fan of solving the standard 9x9 Sudoku puzzles, specially the "Evil" type from...
5. ### Java Java Sudoku Solving Program: Debugging Help Needed

I am attempting to create a Sudoku Solving Program in Java This is what I have to far https://pastebin.com/raw/tgnAGKb2 I have spent close to an hour trying to debug it but to no avail Can someone more skilled than I please point me in the right direction?
6. ### What is the mistake in this Sudoku checker code?

Homework Statement # Sudoku [http://en.wikipedia.org/wiki/Sudoku] # is a logic puzzle where a game # is defined by a partially filled # 9 x 9 square of digits where each square # contains one of the digits 1,2,3,4,5,6,7,8,9. # For this question we will generalize # and simplify the game. #...
7. ### Solving Sudoku: A Logical Approach

How to solve the attached Sudoku without computer or a guess?
8. ### Optimizing Sudoku Determinants: Finding the Minimum and Maximum Values

Homework Statement A while ago someone posted this problem: ----------------------------------------------------------------------------------- Problem 1 (given after a discussion of determinants in week 3/4 of the course): Consider a 9x9 matrix A. We say that A is a Sudoku matrix if it's...
9. ### Fortran A FORTRAN code for solving Sudoku puzzle

For few days I am thinking to write a code in FORTRAN to solve the sudoku puzzle. At first it seams simple but I have no luck writing this code. I am wondering if there is any written code to solve this puzzle. I hope Sudoku puzzle is known for members here. en.wikipedia.org/wiki/Sudoku
10. ### Move Over Sudoku; Studies Show Virtual Worlds Can Be Good for Your Health

A recent story on Forbes.com reported on a new study about the effects of playing massively-multiplayer online games on one’s cognitive abilities. Conducted on a small sample group of 39 adults between the ages of 60 and 77, the study … Continue reading...
11. ### C# Creating a Simple Sudoku Game in C#

Hi ,I want to generate a sudoku game in c sharp.First I will make 3*3 cells sudoku simple,then whole sudoku (9*9) . I ve added to form 9 commoboxes and a star button. When ı click the start button , the programme will fill randomly two cells with 1, 2, or 3 . Then player will fill other empty...
12. ### How to Generate Theorems for an Abstract System like Sudoku?

For an exercise, I want to axiomatize sudoku. I've came up with the definition of the sudoku puzzle in mathematical terms, as well as the definition of a solved puzzle. I'm have trouble going from there to draw theorems from my newly defined system. How does one generate theorems about an...
13. ### C/C++ Efficiently Solving Sudoku in C++

Hey everyone, I'm trying to teach myself C++ and I recalled that a few years ago my Comp Sci major buddy of mine did a sudoku solving program as a project for a class so I decided to tackle it on my own. I'm getting some headway, but I'm having trouble figuring out a way to "brute force"...
14. ### Find Sudoku Algorithm Solutions in Java - n Size

I'm writing a program in java and I need to find an algorithm to calculate all possible sudoku solutions for a board of size n. I don't need to know how to solve it, just how many possibilities there are.
15. ### Determine if a Sudoku puzzle is easy, medium, hard, or evil

I can't find a solution to these questions. Can someone help? 1. An algorithm to determine if a Sudoku puzzle is easy, medium, hard, or evil. 2. For every valid Sudoku puzzle, there exist at least one valid solution. True or false? Proof?
16. ### Mathematics of a Sudoku puzzle

Hello all, I've recently developed an obsession with the game Sudoku. As I seek to lern more about the puzzle game, my ramblings around the internet led me to the wikipedia page describing the mathematics of Sudoku. The portion of interest to me right now is...
17. ### C/C++ Solve Sudoku in C++ with Algorithm.h

You do NOT have to read the entire code to help me. :smile: It's just for your reference. The problem: I keep getting the message that the file 'algorithm.h' can not be opened. But the header file is very much present in the include folder. What do i do? The compiler I'm using is tubo...
18. ### C/C++ Struggling with C++ Code for Sudoku Puzzle

Please help in c++ urgent Argh! I've been trying to work out this problem for an entire week and I'm now at my wits end! I'm supposed to hand in this assignment in 7 hours and am posting my problem here as a last resort. Can i please have someone's assistance in this? I use Dev-C++. Basically...
19. A

### Java Improve Your JAVA Sudoku Game with Helpful Tips - Urgent Project Assistance

Hi guys, I'm being asked to do a mini-project...Basically, i get a code in JAVA and "edit". Editting can be improving the interface, adding exception handling or adding features and so...I chose Sudodu as my topic..after much searching I found this code but I'm out of ideas, what can be improved...
20. ### Efficiently Generating Sudoku Puzzles by Difficulty

I was wondering if there was a more efficient way of generating sudoku puzzles. I already have a method to create puzzles of varying difficulties that goes something like this: - Randomly generate a completed 9x9 solved sudoku - Randomly remove some of the numbers from the matrix (as...
21. ### A Possibly easy for you, but hard for me Question about Sudoku

A "Possibly easy for you, but hard for me" Question about Sudoku How to calculate the maximum number of valid patterns on a 9x9 Sudoku board? I was coding a flash application which is basically a "sudoku solver". This question is not related with qhat I'm doing but just curious. Please...
22. ### Is there any math way to solve a Sudoku

Is there any math way to solve a "Sudoku" I didn,t know where to put this question...my doubt is if there is an exact math way to solve a "Sudoku"...:rolleyes: :rolleyes: ( i don,t think is necessary to explain the game isn,t it?) as far as i know Euler himself "invented" the game about 300...
23. ### Sudoku solving with matricies and/or diophantine equations

I was wondering if there is a way to solve these puzzles with matricies and/or diophantine equations: http://www.sudoku.com/ If you define the basis as nine orthogonal vectors, and input the given initial values to the corresponding places in a 9X9 matrix, and also brake it up into 9 3X3...
24. ### Sudoku scanning and trial and error

Hi, I wondered whether there is any other way to solve these puzzles apart from just scanning and trial and error ? Also is there any relevance to group theory or any other mathematics ? Is there any practical way of solving it mentally ? because I have to write out the various...
25. ### How many possible Sudoku boards are there?

Hi! I've got a couple of questions about Sudoku. 1. How many possible Sudoku boards are there? That is, a 3x3 square of 3x3 blocks where (a) each block has the numbers 1-9 exactly once, and (b) each row and column of the resulting 9x9 matrix has the numbers 1-9 exactly once? 2. I'm...
26. ### Solving the Mysteries of Sudoku

http://en.wikipedia.org/wiki/Sudoku I have found myself addicted to working on them. has anyone else here found these things interesting? I'm currently trying to work out the probability of degeneracy when given a particular square, it has proven challenging...